Stencil sheet and process of producing the same



Patented Aug. 3, 192 6.

-UN'ITED STATES ALEX BROOKING DAVIS, 01 CINCINNATI, OHIO, ASSIGNOR TO A. B. DICK COMPANY, A

PATENT OFFICE.

01 CHICAGO, ILLINOIS, A CORPORAZION OF ILLINOIS.

STENCIL SHEET .AND PROCESS OI PRODUCING THE SAME.

I No Drawing.

This invention is, based upon the discovery that a strong, stable and efiicient stencil sheet, preferably of the flexible, type-impressible variety, may be produced by the" use of metals which may be associated with a suitable fabric such, for example, as the fibrous, porous material known as yoshine, this association being effected in any one of a variety of ways as hereinafter pointed out. A wide range of metals may be employed, either pure or in the form of alloys, a thin film or films thereofbeing employed which may be impressed, as by a stylus or the type of a writing machine, to formopen characters therein through which ink may be passed for the production v of copies upon an underlying impression sheet in the manner practiced in mimeographing. Within this invention one way of effectthe association of the metal with the fa ric sheet is by the reduction of a metallie solution in which the sheet is immersed. Another way is b employing low melting metals or alloys t ereof, such as tin, lea bismuth, cadmium and the ,like, melting these and rolling a thin film thereof between two fabric sheets on a hot plate or in contact with a single fabric sheet, .the fabric sheet or sheets having been, if desired, treated with a suitable strengthening agent, as, for example, an oil-tem ered cellulose such psk acetone-soluble cellu ose acetate or the Another we is to make the fabric'sh'eet (pretreated wlthfa strengtheningl agent as above described or'not) electrica y conductive, as bydusting it with carbon or finely divided metals or impregnating it with certain metallic salts and then to de osit the metal thereon (either o'n one side 0 the fab ric sheet or .both) bythe process of electrodeposition. Or, if desired, a thin metallic film may be applied-to the fabric sheet (which may be pretreated as above described) and permanently attached thereto by a suitable adhesive, as gum damar or sandarac. With stencil sheets prepared in I any of the above ways the type or stylus may make contact direct with such sheet, or through a thin type-protecting tissue, and, if desired, a cushion sheet may be em loyed on which the stencil sheet may rest the process of stencilization, such cushion sheet being preferably of soft paper or other fabric.

uring a porous ase Application filed m a, 1925. Serial No. 29,234.

fvention the following process-may be .em-

ployed. There is prepared a solution of 100 gms. of silver nitrate dissolved in 1000 cc. of water. containing gms. of 26 deg. B. aqua ammonia. With this solution, there is now mixed another solution consisting of 50 gms. of potassium tartrate dissolved in 1000 cc. of water. This mixture is now diluted with ten times its own volume of water, and there are immersed in the resulting bath sheets of yoshino paper which have been previously strengthened by dipping them through a solutlon of modifiedv cellulose acetate in acetone and allowing the acetone to'evaporate. Thesilver nitrate is now rapidly reduced to metallic silver by 'the potassium tartrate, and the silver is deposited in the metallic state as a homogeneous coating upon the yoshino surface. This metallic coating variesin thickness according to the amount of silver deposited orv the time that the sheet is immersed and practically any desired thickness of coating maybe obtained. When the sheets have thus been coated with silyer to the desired extent, they are removed and dried, andthen constitute a t e impressible stencil sheet capable of yielding large numbers of copies when'used on the usual type of duplicating machines. g

If only a thin coating of silver be deposited, the sheets may subsequently be immersed in a plating bath of copperor other metals, and an additional coating of metal deposited thereon electrically 1n known manner.

What I claim is 1. ,A type impressible stencil sheet having a porbus base in association with metal.

I 2. A ty impressible stencil sheet having a; orous ass in association with metallic 3. A ty e impressible stencil sheet having anporous ase in association with a metallic a 0y. I

4.'A ty e impressible stencil sheet having a porous Ease pretreated with a strengthening substance and associated with metal.

5.. A ty e impressible stencil sheet having a porous ase pretreated with astrengthen ing substance and associated with metal foih 6. A ty impressible stencil sheet having ice pretreated with a strengthen- 1 illig substance and associatedwith a metallic a loy. p p 7. In a type impressible stencil sheet, a sheet of porous material, a metallic film, and means for attaching said sheet and film together. I

8. In a type impressible stencil sheet, a

sheet of porous material, a metallic film,

and means for attaching said sheet and film together throughout substantially their entire area. 9. The process of preparing a stencil sheet which consists in pretreating a sheet of porous material to strengthen its structure and then permanently associating the same with a metallic film.

10. The process of preparing a stencil sheet which consists in pretreating a sheet of porous material to strengthen its structure 30 and then permanently associating the same .with a metallic film, said sheet and film being in contact throughout substantially their entire area.

11. The process of preparing a stencil sheet which consists in pretreating a sheet of porous material to strengthen its structure and then permanently associating the same with a metallic film on either side thereof.

12. The process of preparing a stencil sheet which consists in applying metal, in finely divided form, to a porous base, constituting thereon a homogeneous film.

13. The process of preparing a stencil sheet which consists in pretreating a porous sheet to strengthen its structure and applying metal, in finely divided form, thereto, such metal constituting a homogeneous film.

This specification signed this 5th day of May, 1925. vALEX BROOKIN G 'DAVIS. 

